Scottish bacteriologist best known for his discovery of penicillin. Fleming had a genius for technical ingenuity and original observation. His work on wound infection and lysozyme, an antibacterial enzyme found in tears and saliva, guaranteed him a place in the history of bacteriology. But it was his discovery of penicillin in 1928, which started the...

Russian physiologist known chiefly for his development of the concept of the conditioned reflex. In a now-classic experiment, he trained a hungry dog to salivate at the sound of a bell, which was previously associated with the sight of food. He developed a similar conceptual approach, emphasizing the importance of conditioning, in his pioneering studies...

study of the functioning of living organisms, animal or plant, and of the functioning of their constituent tissues or cells. The word physiology was first used by the Greeks around 600 bce to describe a philosophical inquiry into the nature of things. The use of the term with specific reference to vital activities of healthy humans, which began in...

Greek physician, writer, and philosopher who exercised a dominant influence on medical theory and practice in Europe from the Middle Ages until the mid-17th century. His authority in the Byzantine world and the Muslim Middle East was similarly long-lived. Early life and training The son of a wealthy architect, Galen was educated as a philosopher and...

American geneticist and biophysicist who played a crucial role in the discovery of the molecular structure of deoxyribonucleic acid (DNA), the substance that is the basis of heredity. For this accomplishment he was awarded the 1962 Nobel Prize for Physiology or Medicine with Francis Crick and Maurice Wilkins. Watson enrolled at the University of Chicago...

Indian plant physiologist and physicist whose invention of highly sensitive instruments for the detection of minute responses by living organisms to external stimuli enabled him to anticipate the parallelism between animal and plant tissues noted by later biophysicists. Bose’s experiments on the quasi-optical properties of very short radio waves (1895)...

British biophysicist, who, with James Watson and Maurice Wilkins, received the 1962 Nobel Prize for Physiology or Medicine for their determination of the molecular structure of deoxyribonucleic acid (DNA), the chemical substance ultimately responsible for hereditary control of life functions. This accomplishment became a cornerstone of genetics and...

branch of medical science concerned with the nature, function, and diseases of the blood. In the 17th century, Dutch microscopist Antonie van Leeuwenhoek, using a primitive, single-lens microscope, observed red blood cells (erythrocytes) and compared their size with that of a grain of sand. In the 18th century English physiologist William Hewson amplified...

Chinese scientist and phytochemist known for her isolation and study of the antimalarial substance qinghaosu, later known as artemisinin, one of the world’s most-effective malaria -fighting drugs. For her discoveries, Tu received the 2015 Nobel Prize for Physiology or Medicine (shared with Irish-born American parasitologist William Campbell and Japanese...

German physician and one of the founders of bacteriology. He discovered the anthrax disease cycle (1876) and the bacteria responsible for tuberculosis (1882) and cholera (1883). For his discoveries in regard to tuberculosis, he received the Nobel Prize for Physiology or Medicine in 1905. Early training Koch attended the University of Göttingen, where...

German physiologist and psychologist who is generally acknowledged as the founder of experimental psychology. Wundt earned a medical degree at the University of Heidelberg in 1856. After studying briefly with Johannes Müller, he was appointed lecturer in physiology at the University of Heidelberg, where in 1858 he became an assistant to the physicist...

German pathologist and statesman, one of the most prominent physicians of the 19th century. He pioneered the modern concept of pathological processes by his application of the cell theory to explain the effects of disease in the organs and tissues of the body. He emphasized that diseases arose, not in organs or tissues in general, but primarily in...

German medical scientist known for his pioneering work in hematology, immunology, and chemotherapy and for his discovery of the first effective treatment for syphilis. He received jointly with Élie Metchnikoff the Nobel Prize for Physiology or Medicine in 1908. Early life Ehrlich was born into a Jewish family prominent in business and industry. Although...

Austrian zoologist, founder of modern ethology, the study of animal behaviour by means of comparative zoological methods. His ideas contributed to an understanding of how behavioral patterns may be traced to an evolutionary past, and he was also known for his work on the roots of aggression. He shared the Nobel Prize for Physiology or Medicine in 1973...

Canadian physician who, with Charles H. Best, was one of the first to extract (1921) the hormone insulin from the pancreas. Injections of insulin proved to be the first effective treatment for diabetes, a disease in which glucose accumulates in abnormally high quantities in the blood. Banting was awarded a share of the 1923 Nobel Prize for Physiology...

German scientist and philosopher who made fundamental contributions to physiology, optics, electrodynamics, mathematics, and meteorology. He is best known for his statement of the law of the conservation of energy. He brought to his laboratory research the ability to analyze the philosophical assumptions on which much of 19th-century science was based,...

American scientist whose discovery in the 1940s and ’50s of mobile genetic elements, or “ jumping genes,” won her the Nobel Prize for Physiology or Medicine in 1983. McClintock, whose father was a physician, took great pleasure in science as a child and evidenced early the independence of mind and action that she would exhibit throughout the rest of...

Italian physician and physicist who investigated the nature and effects of what he conceived to be electricity in animal tissue. His discoveries led to the invention of the voltaic pile, a kind of battery that makes possible a constant source of current electricity. Early years Galvani followed his father’s preference for medicine by attending the...

Irish-born American parasitologist known for his contribution to the discovery of the anthelmintic compounds avermectin and ivermectin, which proved vital to the control of certain parasitic infections in humans and other animals. For his discoveries, Campbell was awarded the 2015 Nobel Prize for Physiology or Medicine (shared with Japanese microbiologist...

German-born American theoretical physicist who helped shape quantum physics and increased the understanding of the atomic processes responsible for the properties of matter and of the forces governing the structures of atomic nuclei. He received the Nobel Prize for Physics in 1967 for his work on the production of energy in stars. Moreover, he was...

German physiologist who founded modern histology by defining the cell as the basic unit of animal structure. Schwann studied at the Jesuits’ College at Cologne before attending the University of Bonn and then the University of Würzburg, where he began his medical studies. In 1834, after graduating with a medical degree from the University of Berlin,...

American zoologist and geneticist, famous for his experimental research with the fruit fly (Drosophila) by which he established the chromosome theory of heredity. He showed that genes are linked in a series on chromosomes and are responsible for identifiable, hereditary traits. Morgan’s work played a key role in establishing the field of genetics....

operation on a living animal for experimental rather than healing purposes; more broadly, all experimentation on live animals. It is opposed by many as cruelty and supported by others on the ground that it advances medicine; a middle position is to oppose unnecessarily cruel practices, use alternatives when possible, and restrict experiments to necessary...

medical specialty concerned with the determining causes of disease and the structural and functional changes occurring in abnormal conditions. Early efforts to study pathology were often stymied by religious prohibitions against autopsies, but these gradually relaxed during the late Middle Ages, allowing autopsies to determine the cause of death, the...

medical discipline dealing with the role of hormones and other biochemical mediators in regulating bodily functions and with the treatment of imbalances of these hormones. Although some endocrine diseases, such as diabetes mellitus, have been known since antiquity, endocrinology itself is a fairly recent medical field, depending as it does on the recognition...

the scientific study of the body’s resistance to invasion by other organisms (i.e., immunity). In a medical sense, immunology deals with the body’s system of defense against disease-causing microorganisms and with disorders in that system’s functioning. The artificial induction of immunity against disease has been known in the West at least since Edward...

Italian American neurologist who, with biochemist Stanley Cohen, shared the Nobel Prize for Physiology or Medicine in 1986 for her discovery of a bodily substance that stimulates and influences the growth of nerve cells. Levi-Montalcini studied medicine at the University of Turin and did research there on the effects that peripheral tissues have on...

Indian-born American biochemist who shared the 1968 Nobel Prize for Physiology or Medicine with Marshall W. Nirenberg and Robert W. Holley for research that helped to show how the nucleotides in nucleic acids, which carry the genetic code of the cell, control the cell’s synthesis of proteins. Khorana was born into a poor family and attended the University...

British scientist who, with Leland H. Hartwell and Sir Paul M. Nurse, won the Nobel Prize for Physiology or Medicine in 2001 for discovering key regulators of the cell cycle. After receiving a Ph.D. from the University of Cambridge in 1968, Hunt conducted research at the Albert Einstein College of Medicine in New York. He later taught at Cambridge...

the study of the physiological bases of behaviour. Biological psychology is concerned primarily with the relationship between psychological processes and the underlying physiological events—or, in other words, the mind-body phenomenon. Its focus is the function of the brain and the rest of the nervous system in activities (e.g., thinking, learning,...